1 /* 2 * Copyright (c) 1996-1999 3 * HD Associates, Inc. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by HD Associates, Inc 16 * 4. Neither the name of the author nor the names of any co-contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY HD ASSOCIATES AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL HD ASSOCIATES OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * $FreeBSD$ 32 * 33 */ 34 35 /* XXX: The spec says that if _POSIX_C_SOURCE is defined then 36 * _POSIX_SOURCE is ignored. However, this is similar to 37 * the code in the O'Reilly "POSIX.4" book 38 */ 39 40 #define _POSIX_VERSION 199309L 41 #define _POSIX_SOURCE 42 #define _POSIX_C_SOURCE 199309L 43 44 #include <sys/mman.h> 45 #include <errno.h> 46 #include <fcntl.h> 47 #include <limits.h> 48 #include <sched.h> 49 #include <stdio.h> 50 #define __XSI_VISIBLE 1 51 #include <stdlib.h> 52 #undef __XSI_VISIBLE 53 #include <string.h> 54 #include <unistd.h> 55 56 #include "prutil.h" 57 58 static FILE *verbose; 59 60 static void 61 checkpris(int sched) 62 { 63 int smin; 64 int smax; 65 66 errno = 0; 67 68 if ( (smin = sched_get_priority_min(sched)) == -1 && errno) 69 quit("sched_get_priority_min"); 70 71 if ( (smax = sched_get_priority_max(sched)) == -1 && errno) 72 quit("sched_get_priority_max"); 73 74 if (smax - smin + 1 < 32 || smax < smin) { 75 fprintf(stderr, "Illegal priority range for %s: %d to %d\n", 76 sched_text(sched), smin, smax); 77 exit(-1); 78 } 79 80 if (verbose) 81 fprintf(verbose, "%12s: sched_min %2d sched_max %2d\n", 82 sched_text(sched), smin, smax); 83 } 84 85 /* Set "try_anyway" to quit if you don't want to go on when 86 * it doesn't look like something should work. 87 */ 88 static void try_anyway(const char *s) 89 { 90 fputs(s, stderr); 91 fprintf(stderr, "(trying anyway)\n"); 92 errno = 0; 93 } 94 95 static void q(int line, int code, const char *text) 96 { 97 if (code == -1) 98 { 99 fprintf(stderr, "Error at line %d:\n", line); 100 perror(text); 101 exit(errno); 102 } 103 } 104 105 int sched(int ac, char *av[]) 106 { 107 int fifo_schedmin, fifo_schedmax; 108 int i; 109 struct sched_param rt_param; 110 int n_instances = 10; 111 int sched; 112 113 verbose = 0; 114 115 #if _POSIX_VERSION < 199309 116 try_anyway("The _POSIX_VERSION predates P1003.1B\n"); 117 #endif 118 119 #if !defined(_POSIX_PRIORITY_SCHEDULING) 120 try_anyway( 121 "The environment does not claim to support Posix scheduling.\n"); 122 #endif 123 124 /* Is priority scheduling configured? 125 */ 126 errno = 0; 127 if (sysconf(_SC_PRIORITY_SCHEDULING) == -1) { 128 if (errno != 0) { 129 /* This isn't valid - may be a standard violation 130 */ 131 quit("(should not happen) sysconf(_SC_PRIORITY_SCHEDULING)"); 132 } 133 else { 134 try_anyway( 135 "The environment does not have run-time " 136 "support for Posix scheduling.\n"); 137 } 138 } 139 140 /* Check that the priorities seem reasonable. 141 */ 142 143 checkpris(SCHED_FIFO); 144 checkpris(SCHED_RR); 145 checkpris(SCHED_OTHER); 146 147 /* BSD extensions? 148 */ 149 #if defined(SCHED_IDLE) 150 checkpris(SCHED_IDLE); 151 #endif 152 153 fifo_schedmin = sched_get_priority_min(SCHED_FIFO); 154 fifo_schedmax = sched_get_priority_max(SCHED_FIFO); 155 156 /* Make sure we can do some basic schedule switching: 157 */ 158 { 159 struct sched_param orig_param, shouldbe; 160 int orig_scheduler = sched_is(__LINE__, &orig_param, -1); 161 162 if (verbose) 163 fprintf(verbose, 164 "The original scheduler is %s and the priority is %d.\n", 165 sched_text(orig_scheduler), orig_param.sched_priority); 166 167 /* Basic check: Try to set current settings: 168 */ 169 q(__LINE__, sched_setscheduler(0, orig_scheduler, &orig_param), 170 "sched_setscheduler: Can't set original scheduler"); 171 172 rt_param.sched_priority = fifo_schedmin; 173 174 q(__LINE__, sched_setscheduler(0, SCHED_FIFO, &rt_param), 175 "sched_setscheduler SCHED_FIFO"); 176 177 (void)sched_is(__LINE__, 0, SCHED_FIFO); 178 179 q(__LINE__, sched_getparam(0, &shouldbe), "sched_getparam"); 180 181 if (shouldbe.sched_priority != fifo_schedmin) 182 quit("sched_setscheduler wrong priority (min)"); 183 184 rt_param.sched_priority = fifo_schedmin; 185 186 q(__LINE__, sched_setparam(0, &rt_param), 187 "sched_setparam to fifo_schedmin"); 188 189 rt_param.sched_priority = fifo_schedmin + 1; 190 191 q(__LINE__, sched_setparam(0, &rt_param), 192 "sched_setparam to fifo_schedmin + 1"); 193 194 q(__LINE__, sched_getparam(0, &shouldbe), 195 "sched_getparam"); 196 197 if (shouldbe.sched_priority != fifo_schedmin + 1) 198 quit("sched_setscheduler wrong priority (min + 1)"); 199 200 q(__LINE__, sched_setscheduler(0, SCHED_RR, &rt_param), 201 "sched_setscheduler SCHED_RR"); 202 203 (void)sched_is(__LINE__, 0, SCHED_RR); 204 205 q(__LINE__, sched_setscheduler(0, orig_scheduler, &orig_param), 206 "sched_setscheduler restoring original scheduler"); 207 208 (void)sched_is(__LINE__, 0, orig_scheduler); 209 } 210 211 212 { 213 char nam[] = "P1003_1b_schedXXXXXX"; 214 int fd; 215 pid_t p; 216 pid_t *lastrun; 217 218 fd = mkstemp(nam); 219 if (fd == -1) 220 q(__LINE__, errno, "mkstemp failed"); 221 222 (void)unlink(nam); 223 224 p = (pid_t)0; 225 226 write(fd, &p, sizeof(p)); 227 228 q(__LINE__, (int)(lastrun = mmap(0, sizeof(*lastrun), PROT_READ|PROT_WRITE, 229 MAP_SHARED, fd, 0)), "mmap"); 230 231 /* Set our priority at the highest: 232 */ 233 sched = SCHED_FIFO; 234 rt_param.sched_priority = fifo_schedmax; 235 q(__LINE__, sched_setscheduler(0, sched, &rt_param), 236 "sched_setscheduler sched"); 237 238 for (i = 0; i < n_instances; i++) 239 { 240 pid_t me; 241 242 /* XXX This is completely bogus. The children never run. 243 */ 244 if ((me = fork()) != 0) 245 { 246 /* Parent. 247 */ 248 (void)sched_is(__LINE__, 0, sched); 249 250 /* Lower our priority: 251 */ 252 rt_param.sched_priority--; 253 254 q(__LINE__, sched_setscheduler(0, sched, &rt_param), 255 "sched_setscheduler sched"); 256 257 while (1) 258 { 259 q(__LINE__, sched_getparam(0, &rt_param), "sched_getparam"); 260 261 rt_param.sched_priority--; 262 263 264 if (rt_param.sched_priority < fifo_schedmin) 265 exit(0); 266 267 *lastrun = me; 268 q(__LINE__, sched_setparam(0, &rt_param), "sched_setparam"); 269 270 if (*lastrun == me) 271 { 272 /* The child will run twice 273 * at the end: 274 */ 275 if (!me || rt_param.sched_priority != 0) 276 { 277 fprintf(stderr, 278 "ran process %ld twice at priority %d\n", 279 (long)me, rt_param.sched_priority + 1); 280 exit(-1); 281 } 282 } 283 } 284 } 285 } 286 } 287 288 return 0; 289 } 290 #ifdef STANDALONE_TESTS 291 int main(int argc, char *argv[]) { return sched(argc, argv); } 292 #endif 293